Installing a door correctly can be difficult, including installing a pre-hung door. It requires that the door be level and properly spaced within the opening. Correct installation also requires that the reveals of the jamb be parallel with the door on all sides, and that the proper different spacing is present between the door perimeter and the door jamb. But holding the level, shimming and trying to maintain that required spacing is hard and the install usually ends up less than accurate.
Pre-hung doors have additional problems associated with the preparation for shipping and the shipping process itself. Improvements in installation and shipping tools could simplify the door shipping process, the installation process and improve the finished product.